Pneumatic telemetering system



E. H. HART PNEUMATIC TELEMETERING SYSTEM Filed Jan. 16, 1942TRANSMITTERS 2 SheetsSheet 1 4s IH L 59 RECENER FIG. 2

TRANSMITTER FM-il INVENTOR. UGENE H./-/ART 4, 1945. E. H. HART PNEUMATICTELEMETERING SYSTEM 2 Sheets-Sheet 2 Filed Jan. 16. 1942 FIG TO RECEIVERFROM TRANSM ITTERS INVENTOR EUGENE H. HAR 7T "20W ATTORNEY Patented Dec.4, 1945' PNEUMATIC TELEMETERING SYSTEM Eugene H. Hart, Waterbury, Conn.,asslguor to The Bristol Company, Waterbury, Com, a corporation ofConnecticut Application January 16,1942, Serial No. 428,941

9Claims.

This invention relates to fluid pressure operated telemetering systemsand more especially to means for rendering a system of this classadaptable to the transmission to a central station of measurementsperformed at a plurality of more or less diverse points.

It is an object of this invention to provide a telemetering system ofthe pneumatic type in which the pressure of air applied to an indicatingor recording receiving instrument may be made to correspond with thatdeveloped inany selected one of a plurality of transmitting instruments.

It is a further object to provide means whereby the selection of theparticular transmitting instrument which it is desired to associate withthe receiver may be remotely effected by electrical means or locallyeffected by the use of a multi-port valve. I

It is a furtherobject to provide rneans whereby the selection oftransmitting instruments to be successively associated with a receivinginstrument may be carried out automatically, either according to a cyclerepresented by a progressive advance from one transmitter to anotherindividually upon the attainment of a predetermined condition, oraccording to a predetermined cycle upon the attainment of saidcondition, or according to a continuously repetitive cycle.

In carrying out the purposes of the invention it is proposed to utilizethe principles 01' a pneumatic telemetering system wherein atransmitting instrument provided with a sensitive element responsive tochanges in a magnitude to be measured, and remotely indicated orrecorded, is caused to regulate the pressure of air or other elasticfluid in a conduit so that said pressure will at all times be a measureof the value of said magnitude. Such instruments are available in avariety of forms and are compensated for variations in supply pressureand other possible sources of error. The receiving instrument for such asystem embodies the elements of a pressure gauge which latter may be madin either an indicating or a recording form. Such a system oftelemetering and the instrumentalitie's by which its purposes may becarried out-are fully set forth and described in British'Letters' PatentNo. 525,674, issued to the applicant's assignee on September 2, 1940.

The nature of th invention, however, will best be understood whendescribed in connection with the accompanying drawings in which:

' Fig. 1 is a diagrammatic representation of a 55 communication with theatmosphere, thus tend transmitting instrument suitable for use in asystem embodying the principles of the invention.

Fig. 2 is a diagrammatic representation of a multiple-point telemeteringsystem embodying the principles of the invention.

Fig. 3 is a representation of motor-driven valve means whereby selectionof transmitters may be automatically carried out according to apredetermined cyclical schedule.

Fig. 4 is the diagram of an electrical circuit which may'alternativelybe used with 'the embodiment of the invention shown in Fig. 3.

Figs. 5 and 6 are front and side elevations, respectively, of afluid-pressure actuated electrical contactor which may eiiectively beused with some forms of the invention.

Referring now to the drawings: In Fig. 1, the numeral= I0 designates abase-plate upon which are mounted the several elements comprising atransmitting instrument. A primary measuring unit ll carries anindicating pointer l2 adapted to deflect in response to changes in themagnitude of the condition to be measured and to provide on a graduatedscale [3 a direct indication of said magnitude. Also mounted upon theplate I0 is an orifice member l4, having in cooperative associationtherewith a vane element l5 carried upon an extended arm l6, pivotallymounted upon the base-plate ill at the extremity of the arm remote fromsaidvane member. tive positioning and interaction of the vane andorifice members is such that a very small movement of the vane withrespect to the orifice may produce a large change in the equivalentopening of said orifice and a, correspondingly large change in backpressure of air or other pressure fluid escaping therefrom.

Mounted upon the base-plate In is a. threeway valve of thesupply-and-waste type having a body portion l1 and a stem portion l8,profluid pressure is positioned on the base-plate In 'for operativeengagement with the stem member IS. The arrangement is such thatincrease of pressure within the bellows 2! tends to operate the valve ina sense to impede the supply of pressure fluid to the port 19 from thesupply 20 and at the same time to place said port in freer The relav ingto lower thepressure at the port l9 and in any closed system which maybe connected therethe orifice unit l4 in'relation to theresistanceopposed to passage of pressure fluid through the constriction23, thus will be communicated to the bellows member 2| and render theefiect of the valve subject to the position of the vane l5.

Connected to the port IQ of this valve is a closed system including aconduit 24 which ex tends from the transmitting instrument to the pointwhere remote measurement is required. A Bourdon spring 25 of theconventional type and mounted on base-plate I is in communication withthe conduit being adapted to deflect in response to changes in thepressure of the fluid therein. a

A verticallyextended floating lever member 23 having three pivotbearings, one at each extremity and one intermediately located, ispivotally mounted by the latter bearing upon the arm l at a pointintermediate the vane member l5 and the point of pivoting of said armupon the base-' I free end of the Bourdon spring 25.

With the connections made as shown in Fig. 1, it will be apparent thatupondeflection of the pointer l2 in response to a change in the value ofthe condition as measured upon the scale l3 by the element II, forexample to the right, the upper end of the floating lever 25 will bedeflected toward the left. The vane l5 will be similarly deflected,tending to obstruct the outlet of the orifice member l4 and retard theescape of air therefrom The pressure within the conduit 22 being subjectto the escape of air relative to its supply through the constriction 23,will tendto rise, which increase of pressure, being communicated to thebellows member 2|, will cause said bellows to expand. This effectsmovement of the stem N3 of the three-way valve in a sense to cut off theadmission of air from the supply 20, and to increase the vent to theatmosphere, with a consequent lowering of pressure in the closed conduit24 and all parts of the system in communication therewith. Thisreduction of pressure, being communicated to the Bourdon spring 25, willcause its free end to be deflected toward the right, setting through thelink 28 to move the lower end of the floating lever 25 in the samedirection, tending to annul the original motion of the vane l5 towardthe left.

In a similar manner, the result of a deflection of the pointer I2 towardthe left, and a consequent movement of the vane l5 toward the right,will be to lower the pressure in the bellows 2|. This will cause thepressure in the conduit 24 to be increased, deflecting the free end ofthe Bourdon spring 25 toward the left, similarly moving the lower end of.the lever 26 and the vane l5, and establishing a balance with a newvalue of pressure in the conduit 24. Thus, the tendency of the devicewill be to establish and maintain at all times a condition of balancewith the edge of the vane l5 at a point with respect to the orificemember l4 where the resulting pressure in'the bellows 2| will cause thevalve to be maintained in a condition to hold in the conduit 24 a fluidpressure which shall bear a definite re- 5 lation to the position of theindicator l2 in regard to the scale l3.

The receiving instrument may take the form of a pressure gauge of anyconventional type and may be adapted to provide its ultimate measure-.10 ment either in the form of an indication or a record. The receivinginstrument is connected to conduit 24 o! the transmitting instrument;and since the only flow of pressure fluid through said conduit is thatwhich takes place upon a "change in the pressure established therein bythe transmitting instrument, the conduit may be of an extremely smallbore and yet provide an eflective pressure measurement at the receivinginstrument. r

In Fig. 2 is shown an arrangement whereby a single receiving instrumentmay be selectively placed in operative connectiomwith any one 0! fourtransmitting instruments 3|, 32, 33 or 34, of the type hereinbefore setforth, situated at '25 points more or less remote from each other andfrom the receiver. The transmitters are, connected each to receive asupply of air, as from sources 35, 36, 31 and 38, or from a commonsource if expedient, and to modify the pressures in outlet conduits 39,40, 4| and 42 respectively,

in accordance with changes invalues measured by said transmitters. Thefour conduits 33, 40, 4| and 42 are connected through electricallyactuated valves 43, 44, 45 and 45 respectively to a common conduit 41,which in turn leads to a receiving instrument 48, which may take theform of an indicating or recording pressure gauge, having a scalecalibrated in terms 01 the magnitudes under measurement by the transmit-40 ting instruments.

tors 54, 5s, and 51, carries also a switch arm 53 adapted to provideelectrical connection with any one of said contact elements. The treeterminals of the electrically actuated valves are connected by means ora commonconductor 59 0 to one terminal of a source of electrical energyand the other terminal of said source by a conductor 6| to the switcharm 58 of the dial switch 49.

The several valves being so arranged as to be 55 opened upon electricalenergization and closed upon deenergization, it will be seen that withthe switch arm 58 brought into engagement with a selected one of thecontact elements in the dial switch, the corresponding valve in thepiping 60 system will be energized and opened, and the receivinginstrument made responsive to pressure variations controlled by thecorrespondingtransmitter. For example, with the switch arm set on thecontact element 5|, the valve 44 will be v opened, and the receiver 48made responsive to pressure values in the conduit 40, thus to provide aremote indication or record of quantities de-' termined by thetransmitting instrument 32.

In Fig. 3 is shown apparatus whereby selective action may be madeautomatically to carry out a cycle whereby respective transmittinginstruments are successively connected to a single receiving instrumentaccording to any one of sevveral desired cycles. A transfer valve 15, ofthe Piston type, comprises an elongated body portion II axially boredtherethrough and having four spaced ports communicating respectivelywith the conduits 88, 48, 4| and 42, which in turn are connected to theseveral transmitting instruments as shown in Fig. 1. correspond ingports are provided with a common connection to the conduit '41. A pistonorplunger 11 adapted to be moved longitudinally within the bore of thebody part 18 is provided with circumferential grooves I8 spaced evenlytherealong. but differently to the spacing between the ports in the bodypart. The spacing of the grooves I8 is related to that of said ports insuch a manner that as the plunger 11 is moved longitudinally within thebody part I8 the conduits 88, 48, 4| and 42 will be selectively and oneat a time placed in communication with the conduit 41 according to thelongitudinal position of said plunger. Thus by a longitudinal movementof the plunger I! a selected one of the several transmitting instrumentsmay be placed in operative association with the single receiver.

The plunger TI is provided with a stem 88 adapted to engage the surfaceof a cam 8| having four distinct dwells, whereby the longitudinalposition of the plunger ll will depend upon the angular position of thecam 8|. An electric motor 82 having a shaft 88 is adapted to drive thecam 8| through a train consisting of two operatively engaging gears 84and 88, the former being fixed to the shaft 88 and-the latter to the cam8|. As shown in the drawings the gear 88 is made of four times thediameter of the gear "had that upon one revolution of the shaft 88 thecam 8| willbe advanced A of a revolution and the plunger 11 will beshifted sumciently far to change the communication ofthe-receivinginstrument from one to another of the transmittinginstruments. Mounted upon the shaft 88 is a cam 88 having in its contoura single notch 81. A cam follower 88 is adapted to engage the contour ofcam 88 and to actuate electrical contacts 88 in a sense to close saidcontacts when said follower rests upon the periphery of the cam 88 andto open the same when said follower rests within the notch 81. Connectedto the conduit 41 is a capsular spring or bellows 88 adapted to actuateelectrical contacts 8| in a sense to close said contacts upon theattainment of a predetermined fluid pressure within said bellows and toopen said contacts when pressure within said bellows falls below thepredetermined value. A pair of terminals 82 upon said motor-82 provideconnection between its internal windings and an outside circuit in sucha manner that when electrical energy is applied to said terminals theshaft 88 of said motor will rotate in a clockwise sense. .From one sideof a source ofelectrical supply 88 a conductor 84 is directly connectedto one of the terminals 82.

. From the other side of said source of electrical energy a conductor 88is connected to one side of each of the contacts 88- and 8|. A conductor88 is connected to the other side of each of said contacts 88 and 8| andto the other one of said terminals 82. A manually operable sw tch 81 isconnected between conductors 88 and 88'.

In operation the device as shown in Fig. 3 perthe mechanism are shown ina position where the conduit 48 and the corresponding trans.- mitter arein communication with the conduit 41 and the receiving instrument. Thecam follower 88 rests in the notch 81 on the cam 88.maintain- 8 an opencircuit at the contacts 88. Pressure in the bellows 88 is below thepredetermined critical value, whereby an open circuit is maintained atthe contacts 8|. The switch 81 isstandini; open. Under this conditionthere is no complete circuit between the source of electrical energy 88and the motor 82, so that said motor remains at rest. Pressure in theconduit 48, and therefore in the conduit 41, is controlled by thetransmitting instrument with which these conduits communicate, and solong as this pressure does not exceed the set value of the bellows 88.the receiving instrument will continue to provide a measure ofthemagnitude determined by the transmitting instrument connected to conduit48. Upon the pressure in conduit 41 exceeding the set value of thebellows 88 the contact 8| will be closed, completing a circuit throughconductors 85,- 88 and 84 to the motor 82" and causing the shaft 88 tobe rotated and the cam 8| to be placed. in motion. Immediately upon thecam 88 commencing to rotate; the cam follower 88 will rise to theperiphery of the cam and will close the contacts 88, thus maintainingthe motor 82 in operation without respect to changes in pressure in thebellows 80. The shaft 88 of the motor 82 will thus continue to rotatefor one complete revolution and will cause the cam 8| to berotatedflthrough of a. revolution, moving the plunger 11 to an extent toshift connection of the conduit 41 from the conduit 40 to the conduit4|, thus substituting the transmitting instrument connected to thelatter conduit for that connected to the former conduit.

4 forms inthe following manner: the elements of If the pressure derivedfrom the conduit 4| and communicated'to the conduit 41.1 is less thanthe set value of ,the bellows 88, the contacts 8| 'will be opened; andupon the-completion of one revolution of the shaft 88 and the cam 88 thefollower 88 will drop into the notch 81, opening the contacts 88 andbringing the motor to'rest. thus completing the cycle of shifting onetransmitter to another in the telemetering system. The system as abovedescribed is suited to an installation where the operating pressures inthe conduits 48, 4|, etc., tend to increase from a low value to a highvalue during a cycle of operation. It will be apparent that by replacingthe normally open bellows-atcuated contact 8| by a form adapted to closeon low pressure and be opened by a high pressure, the system will berendered applicable to an installation characterized by progressivelydecreasing pressure values.

As hereinbefore pointed out, the gears 84 and 85 as shown in thedrawings are made with a 1/4 ratio, or in general, a ratio such that onerevolution of the motor shaft 88 will shift the connection of thereceiver from one transmitter to another and will then allow thetransfer valve to come to rest. By substitutinggears having a 1/1 ratiofor gears having a 4/1 ratio, the cam 8| will be caused to rotate at thesame speed as the shaft 83, so that the'complete cycle as determined bythe cam 88 will involve connecting in turn each of the severaltransmitting instruments to the receiver. Thus, upon the attainment ofthe predetermined. pressure in the conduit 41. the motor 82 willautomatically make a "survey of the pressures developed by the severaltransmitting instruments, allowing each of these to afl'ect the receiverfor a time, and will termined by the receiver.

In Figs. 4, and 6 are shown electrical apparatus and circuits which maybe utilized instead of the electrical system shown in Fig. 3, with aview to rendering the motor 62 operating the transfer valve 15responsive to conditions difiering from those by which the apparatusshown in Fig. 3 is normally adapted to be actuated.

The motor 82 and the cam 66 driven thereby,

together with the contacts 89 and operating means therefor, areidentical with the corresponding elements shown in Fig. 3. The bellows90 of Fig. 3, with its single pair of electrical contacts, is replacedby a pressure-switch I00, shown in detail in Figs. 5 and 6, having anoperating bellows, capsular spring, or the equivalent, IOI,

adapted to be longitudinally deformed in response to changes in fluidpressure therein. Carried by the bellows member I0 I, but insulatedtherefrom,

and adapted to be moved by deflection thereof is an insulated contactingmember I02. Slidably mounted on the base of the switch I00 is a bracketI06 adapted for adjustment in the direction of travel of the contactingmember I02 and to be secured to said base in any desired adjustedposition, as by screws 'I0l.. Carried by the bracket I03, but insulatedtherefrom, as by insulatingblocks I05, are contacts I06 adapted to beengaged and bridged by the contacting member I02 as said member attainsthe high limit of its excursion corresponding to a predetermined maximumpressure within the bellows IOI "Slidably mounted on the base of theswitch I00 is a bracket I 01 adapted for adjustment in a sense similarlyto'the bracket I03, but independently thereof and to be secured to thebase as by screws I brackets I03 and I01, the maximum and minimumoperating limits of operation of the pressure switch I 00 may beindependently adjusted. It will be understood that the contacts 9|,shown in Fig. 3, are adjustable in a manner similar to the contacts I06herein described.

A relay "2 (see Fig. 4) is adapted when energized to close two sets ofcontacts 3 and I, and when de-energized to open both said sets ofcontacts. A source of electrical power I I6 is represented by twoconductors H6 and 1. Conductor H6 is connected to one side of each ofthe contacts 3 and 69. ConductorlII is con- -nected to one side ofcontact H0 or the pressure switch I00, to one of the two terminals 92 onthe motor 82, and to one side of the operating coil of relay II2. Aconductor '8 connects'one side of contact I06 to one side of contactIll, and

is also tied to conductor II6 througha resistor 70' nected to each otherand to the remaining one or the terminals 82 on the motor 82 by means ofa conductor "I. n desired, a reversing switch I22 may be interposedbetween the contacts oi the pressure-switch I00 and the conductors II6and bellows IN is low, and that th motor 62,

has come to rest with the cam 66 in the post tion shown wherein thecontact 89 is open, the

relay I I2 will be de-energized and will stand with its contacts H8 andIll both open; and there will b no complete circuit between the sourceH5 and the terminals 92 of the motor 62. The plunger 11 of the transfervalve I6 (as shown in Fig. 3) will thusremain at rest, and the receivinginstrument will provide a measure of conditions as determined by thetransmitting in-. strument whose interconnecting conduit is at that timein communication with the conduit 41.

This condition will continue until pressure in the conduit 61 and in thebellows IOI rises to a value where contacts IIO are opened and contactsI06 closed. Upon closing of the contacts I06, a circuit is completedfrom the conductor 1 I 6 through the resistor. H9, the conductor 8, thecontacts I06, the conductor I20, and the winding of relay II2 to theconductor II'I, thus energizing said relay. The closing of the contactsof the relay II2 eflfects two purposes. Completion of the circuit atcontacts III serves to bridge the contacts I06, and thus to lock therelay in its energized position whether or not said contacts I06 remainclosed. Closing of the contacts H3 connects conductor I2l to conductor II6, thus permitting voltage to be applied to the terminals 92 of themotor 82, causing said motor to rotate the cam 66 and all other elementsoperated by the motor. Immediately upon the commencement of rotation ofcam 86, the contacts 69 will be closed, thus bridging the contacts 6 ofthe relay 2 and rendering it impossible for the motor 62 to bede-energized with the cam 86 in any position other than that from whichit started. So long as the relay II2 remains energized the motor 62 willcontinue to operate; and'should said relay become de-energized, openingthe contacts "6, said motor will continue to operate until the cam 66comes to its starting position, causing the circuit to the motor to bebroken at the contacts 69. There is thus established a definite stoppingposition for the motor 82, so that the transfer valve operated therebycan be brought to rest only in one of its definite settings andnot inany intermediate position. ,By virtue of the completion of the circuitthrough locking contacts II 6, de-energization of the relay II 2 willnot be effected upon the opening of the contacts I06 due to-a loweringof pressure within the bellows IOI below the value established by thesetting of 5 the contacts I06 as positioned by the adjustable Il9. Thefree sides of contacts I06 and H0 are tied together by means of aconductor I20 which is connected also to the free side of contact I I4and to the free end or the operating coil of relay I I2.

bracket I03. In order for the relay Hz to become de-energized, it isnecessary that the pressure within the bellows IOI fall to a valuecorresponding to the setting of the contacts I I0 as positioned by theadjustable bracket I01. Upon closing of the contacts IIO, the conductorI20 will be directly connectedto conductor 1, thus short-circuiting thewinding of relay H2, and momentarily allowing current to flow from con-The tree sides otcontacts 69 and .I I6 are con- 7 ductor 6 throughresistance II9, conductor II6,

contacts I II, conductor Ill, and contacts IIII, to conductor I I1. Uponde-energization of the winding of relay H2 due to its short-circuitingby contacts IIII, the armature of said relay will be released andcontacts H3 and I II both opened. The opening of contacts Ill will breakthe circuit through which resistance I III was momentarily connectedacross the supply; and the opening of contacts H3 will interrupt thesupply of current to the motor 82, except in so far as contacts 89,bridging contacts I I3, may still continue to carry current, whichcondition, as hereinbefore set forth, will be maintained until contactsI! are opened by the cam 86 and the motor 82 brought to rest in apredetermined position. Thus, with the control circuit shown in Fig. 4there is provided an arrangement whereby the transferring of thereceiving instrument selectively from one transmitter to another may beinitiated upon the pressure applied to said receiving instrumentexceeding an adjustable predetermined value. and may be terminated uponsaid pressure decreasing until it attains another adjustablepredetermined minimum value; and by use of the reversing switch I22 ashereinbefore set forth, the functions of the contacts I05 and II Il maybe interchanged, so that initiation of the transfer'cycle will takeplace upon the attainment of a predetermined minimum pressure, andtermination of said cycle upon the attainment of a predetermined maximumpressure. Other combinations of starting and stopping functions whichmay be eflected without departing from the spirit of the invention willsuggest themselves to those versed in the art.

The terms and expressionswhich I have emcontrol a fluid pressure incorrespondence with a measured magnitude, a single pressure-sensitivereceiving instrument, conduit means adapted to connect said transmittinginstruments to said receiving instrument, valve means adaptedselectively to provide operative communication through said conduitmeans between said receiving instrument and any one of said transmitting instruments, power-operated means for ac-- tuating said valve meansthrough a cycle whereby said receiving instrument is rendered responsiveto said transmitting instruments in a predetermined succession, andpressure-sensitive means for actuating said valve means through a .cyclewhereby said receiving instrument is rendered responsive to 'saidtransmitting instruments in a predetermined succession together withmeans responsive to the attainment of a predetermined value by one ofsaid magnitudes, to control a supplyoi power to said power-operatedmeans.

3. In a fluid-pressure-actuated telemetering system: the combination ofa plurality of transmitting instruments each of which is adapted tocontrol a fluid pressure in correspondence with a measured magnitude, asingle pressure-sensitive receiving instrument, conduit means adapted toconnect said transmitting instruments to said receiving instrument,valve means adapted selectively to provide operative communicationthrough said conduit means between said receiving instrument and any oneof said transmitting instruments and power-operated means for actuatingsaid valve means through a cycle whereby said receiving instrument isrendered responsive to said transmitting instruments in a predeterminedsuccession together with means responsive to the attainment of apredetermined pressure in said conduit means to control a supply ofpower to said power-operated means.

4. In a fluid-pressure-actuated telemetering system: the combination ofa plurality of transmitting instruments each of which is adaptedto-control a fluid pressure in correspondence with a measured magnitude,a single pressuresensitive receiving instrument, conduit means adaptedto connect said transmitting instruments to said receiving instrument,valve means adapted selectively to provide operative communicationthrough said conduit means between said receiving instrument and any oneof said transmitting instruments and power-operated means for actuatingsaid valve means through a cycle whereby said receiving instrument isrendered responsive to said transmitting instru- .ments in apredetermined succession, together means for controlling the operationof said ments to said receiving instrument, valve means adaptedselectively to provide operative communication through said conduitmeans between said receiving instrument and any oneof said transmittinginstruments and power-operated 5. In a fluid-pressure-actuatedtelemetering system: the combination of a plurality of transmittinginstruments each of which is adapted to control a fluid pressure incorrespondence with a measured magnitude, a single pressure-sensitivereceiving instrument, conduit means adapted to connect said transmittinginstruments to said receiving instrument, valve means adaptedselectively to provide operative communication through said conduitmeans between said receiving instrument and any one of said transmittinginstruments and power-operated means for actuating said valve meansthrough a cycle whereby said receiving instrument is rendered responsiveto said transmitting instruments in a predetermined succession togetherwith means responsive to the attainment of a selected pressure value insaid conduit means to initiate the operation of said power-operatedmeans, and means responsive to the attainment of another selectedpressure value in said conduit means to terminate said operation.

, 6. In a fluid-prssure-actuated telemetering system: the combination ofa plurality of transmitting instruments each of which is, adapted tocontrol a fluid pressure in correspondence with a measured magnitude, asingle pressure-sensitive receiving instrument, conduit means adapted toconnect said transmitting instruments to said receiving instrument,valve means adapted selectively to provide operative "communicationthrough said conduit means between said receiv;

- ing instrument and any one oi. said transmitting instruments andpower-operated'means for actuating said valve means through a cyclewhereby said receiving instrument is rendered responsive. to saidtransmitting instruments in a predetermined succession together withpressuresensitive means responsive to the attainment of a predeterminedvalue by one of said magnitudes, to control a supply of power to saidpower-operated means.

7. In a fluid-pressure-actuated telemetering system: the combination ofa plurality of transmitting instruments each of which is adapted tocontrol a fluid pressure in correspondence with a measured magnitude, asingle pressure-sensitive receiving instrument, conduit means adapted toconnect said transmitting instruments to said receiving instrument,valve means adapted selectively to provide operative communicationthrough said conduit means between said receiving instrument and any oneof said transmitting instruments and power-operated means for actuatingsaid valve means through a cycle whereby said receiving instrument isrenderedresponsive to said transmitting instruments in a predeterminedsuccession, together with pressuresensitive control means responsive tothe attainment of a predetermined value by one of said magnitudes toinitiate the operation of said power-operated means, and meansresponsive to the attainment of a predetermined value by one of saidmagnitudes to terminate said operation.

I 8. In a fluid-pressure-actuated telemetering system: the combinationof a plurality oi! transmitting instruments each of which is adapted tocontrol a fluid pressure in correspondence with of a selected pressurevalue in said conduit means to initiate the operation of saidpower-operated means, and means responsive to the attainment of anotherselected pressure value in said conduit eans to terminate saidoperation.

9-. a a fluid-pressure-actuated telemetering systeiii: the combinationof a plurality of transmitting instruments each of which is adapted to-control a fluid pressure in correspondence with a measured magnitude, asingle-pressure-sensitive receiving instrument, conduit means adapted toconnect said transmitting instruments to said receiving instrument,electric motor means, valve means actuated thereby upon energizationthereof selectively to provide operative communication through saidconduit means between said receiving instrument and any one of saidtransmitting instruments, and means responsive to the attainment of apredetermined condition in said system for energizing said motor means.

EUGENE H. HART.

